There exist endovascular stent grafts which can be deployed into the vasculature in the region of the aortic bifurcation so as to treat aortoiliac aneurysms. These stent grafts can include an anastomosis in the region of the iliac bifurcation. Such stent grafts require the insertion of a covered stent to bridge the gap between the endovascular graft and the internal iliac artery. A preferred method of introducing the covered stent is to insert the stent through the iliac/femoral artery on the contralateral side and guide the stent up and over to the ipsilateral side where it is deployed (the “up and over” approach). With some stent grafts, a fenestration or valve is provided in the wall of the stent graft to allow temporary access for a catheter to allow deployment of the covered stent through the iliac/femoral artery. Such fenestrations or valves should be self-closing which complicates the stent graft and provides a potential leakage area.
The “up and over” approach from the contralateral side helps to maximize the diameter of the curve available for the covered stent to come around and face caudally so that it can be deployed. Maximising this curve reduces the force required to insert the sheath and catheter constraining the covered stent and also prevents kinking and facilitates easier access.
In patients with shorter common iliac arteries, the “up and over” approach becomes more challenging as the endovascular graft typically has to be inserted further above the aortic bifurcation which reduces the diameter which the sheath has to turn. Furthermore, stent grafts having fenestrations or valves are difficult to design and manufacture for patients with short common iliacs because of the lack of room on the stent graft in the region of the common iliac.
It is an object of the present invention to provide an improved stent graft that ameliorates the aforementioned problem(s) or at least offers a useful choice.
Throughout this specification, when discussing the application of this invention to the aorta or other blood vessels, the term “distal” with respect to a prosthesis is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further downstream with respect to blood flow; the term “distally” means in the direction of blood flow or further downstream. The term “proximal” is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further upstream with respect to blood flow; the term “proximally” means in the direction opposite to the direction of blood flow or further upstream.